This invention relates to microscopes employing optical elements which must be accurately aligned and having a plurality of readily interchangeable optical members which must also be individually and accurately located relative to a certain member or members in the optical system of the instrument. The invention is particularly useful in phase microscopy but could also be used advantageously in other forms of microscopy.
In the Osterberg et al. U.S. Pat. No. 2,427,689, issued Sept. 23, 1947, is shown and described a phase contrast microscope. The use of such an instrument for the examination of substantially transparent materials and objects, such as protozoa, bacteria, body tissues, blood, glass, plastics and the like, has considerably extended the boundaries of microscopy.
U.S. Pat. No. 2,565,419 to Aitcheson describes a turret assembly useful with the Osterberg et al. patent. Aitcheson teaches that a plurality of apertures may be mounted on a single sub-stage turret assembly to accommodate the lighting requirements of several different objectives with a single fixed condenser.
During the use of a phase microscope, it may be desirable to use any one of several different objectives of different powers. It will generally be desirable to interchange the aperture member in the condenser assembly so as to function to best advantage therewith. Also, it is usually desirable to interchange birefringent elements and it is frequently desirable to rapidly change from an air to oil immersion condenser as well as from one technique to another. However, regardless of the reasons for the changing of aperture, birefringent elements, or condensers, it has been found highly essential that proper exact predetermined spacing and alignment of each optical member of the sub-stage assembly to be used with the optical axis of the microscope be effected for best functioning of the microscope.